Benkeser reaction

The Benkeser reduction reaction is the hydrogenation of polycyclic aromatic hydrocarbons, especially naphthalenes using lithium or calcium metal using low molecular weight alkyl amines as the solvent and, in part, as a source of protons. This reaction is a modification of the Birch reduction, where ammonia is the solvent. It offers the advantage that the reactions can be conducted at temperatures higher than the boiling point of ammonia (-33 °C).

For the reduction naphthalene with lithium in a mixed ethylamine-dimethylamine solution, the principal products are bicyclo[3.3.0]dec-(1,9)-ene, bicyclo[3.3.0]dec-(1,2)-ene and bicyclo[3.3.0]decane.